1. Field of the Invention
The present invention relates to an endoscope which is employed for treatment of an affected area and in which a guide wire is made to project from a distal-end opening provided in a treatment instrument insertion channel of an insertion portion and used as a guide to guide a treatment instrument to the affected area.
2. Description of the Related Art
According to conventionally known techniques, an operator carries out various treatments in body cavities by inserting an endoscope into the body cavities, selectively inserting various treatment instruments into a treatment instrument insertion channel arranged in an insertion portion of the endoscope, and projecting the treatment instrument from an opening provided at a distal-end portion of the endoscope.
The endoscope employed for the above treatments has a member (hereinafter referred to as distal-end hard portion), in which elements such as an objective lens are arranged, at a distal end of the insertion portion. In the distal-end hard portion, a tube-like member is arranged. The tube-like member penetrates the distal-end hard portion so as to guide the treatment instrument inserted into the treatment instrument insertion channel therein. A distal-end opening of the tube-like member is communicated with the opening of the distal-end portion of the endoscope. Further, an outer circumference of a proximal end of the tube-like member fits to an inner circumference of the distal end of the treatment instrument insertion channel, and is secured thereby. A proximal end of the treatment instrument insertion channel opens in an operation portion of the endoscope.
In recent years, so called side-looking type endoscopes provided with an imaging optical system on a side surface of a distal end of the insertion portion are employed for treatments of affected areas in alimentary tract system, pancreaticobiliary duct system, and the like. The side-looking type endoscope is employed for treatments of pancreaticobiliary duct system or the like, for example, for a preparatory treatment, in which contrast study is performed on a bile duct or a pancreatic duct with the endoscope, and for a therapeutic treatment, in which a gallstone present in a common bile duct or the like is removed with a use of a balloon, a grasper, or the like.
Since the pancreatic duct, bile duct, hepatic duct, and the like are extremely thin ducts, the insertion of the distal-end portion of the insertion portion of the endoscope into these ducts at the endoscopic treatment of the pancreatic duct, bile duct, hepatic duct, and the like is difficult to perform. Hence, the operator generally achieves the insertion of the insertion portion by: inserting the distal-end portion of the insertion portion of the side-looking type endoscope up to an area near a duodenal papilla, inserting a guide wire into a relevant duct from the side surface of the distal end of the insertion portion, in other words, through the opening provided at the distal end of the treatment instrument insertion channel in the insertion portion, under radioscopy, and selectively inserting a treatment instrument such as a catheter into the pancreatic duct, bile duct, or hepatic duct using the guide wire as a guide.
When the guide wire or the treatment instrument is to be inserted into the relevant duct from the opening in the distal end of the treatment instrument insertion channel in the insertion portion, a so-called treatment instrument riser is raised. The treatment instrument riser is arranged near the opening in the insertion portion and serves to change a direction of advance of the guide wire or the treatment instrument from a direction within the insertion portion of the endoscope to a direction toward the opening formed on the side surface.
According to the above technique, once the guide wire is inserted into a thin duct such as the pancreatic duct, bile duct, or hepatic duct, the treatment instrument can be inserted into and withdrawn from the above mentioned duct repeatedly.
When the treatment instrument is withdrawn from the pancreatic duct, bile duct, or hepatic duct, the guide wire is sometimes withdrawn together with the treatment instrument against the will of the operator due to close contact between the treatment instrument and the guide wire. Since the pancreatic duct, bile duct, or hepatic duct is an extremely thin duct, as described above, the insertion of the guide wire thereinto is difficult to perform. Therefore, it is extremely cumbersome and troublesome for the operator to reinsert the guide wire into the pancreatic duct, bile duct, hepatic duct or the like many times.
Hence, when the operator withdraws the treatment instrument, an assistant of the operator must keep inserting the guide wire toward the pancreatic duct, bile duct, or hepatic duct in order to prevent the withdrawal of the guide wire from the duct. Such an operation is extremely cumbersome for the operator and the assistant. As a result, the endoscopic diagnosis and treatment require high personnel cost, thereby placing a high financial burden on both the hospital and the patient.
In view of the foregoing, Japanese Patent Application Laid-Open No. 2002-34905, for example, proposes a technique for securing the guide wire at a certain position by: withdrawing the treatment instrument from the duct farther than a position where the guide wire is folded by the treatment instrument riser; rotating a treatment instrument riser operation knob provided rotatably in the operation portion; further raising the treatment instrument riser and thereby the guide wire; and sandwiching the guide wire between the treatment instrument riser and the distal end of the insertion portion of the endoscope.
The above-proposed structure is advantageous in that the guide wire would not be withdrawn from the duct when the treatment instrument is withdrawn, since the guide wire is secured between the treatment instrument riser and the distal end of the insertion portion of the endoscope.